The LDDRD has discovered, or has contributed critically to the discovery of eleven new agents described herein which subsequently have been selected by the NCI Decision Network Committee for drug development. These include antitumor compounds: 9-methoxy-2-methyl ellipticinium, halichondrin B and halomon; and, anti-HIV compounds: cyanobacterial sulfolipid, prostratin, michellamine B, calanolide A, 7,8- dihydrocalanolide A, costatolide, 7,8-dihydrocostatolide and conocurvone. LDDRD researchers are continuing to elucidate the novel bioactivities and mechanisms of action of these leads and are supporting expeditious preclinical development whenever possible.